<template>
  <div class="bg-login">
    <canvas id="canvas" class="canvas"></canvas>
  </div>
</template>

<script lang="ts">
import { Component, Provide, Vue, Prop, Watch, Emit } from "vue-property-decorator";

@Component
export default class BgLogin extends Vue {
  @Prop() pagename: string

  // @Provide() config:object = 
  @Watch('pagename')
  onChildChanged (val: string, oldVal: string) {
    console.log(val, oldVal)
    this.createBackground()
  }

  mounted() {
    console.log(this.pagename)
    this.createBackground()
  }

  @Emit() 
  createBackground() {
    let canvas = document.querySelector("canvas"),
    ctx = canvas.getContext("2d");
    canvas.width = window.innerWidth;
    canvas.height = window.innerHeight;
    ctx.lineWidth = 0.3;
    ctx.strokeStyle = new Color(0).style;

    // var mousePosition = {
    // x: 30 * canvas.width / 100,
    // y: 30 * canvas.height / 100
    // };
    let mousePosition = {
      x: canvas.width - 100,
      y: canvas.height - 60
    };

    let dots = {
      nb: 150,
      distance: 100,
      d_radius: 150,
      array: []
    };
    let isMobile = /Android|webOS|iPhone|iPad|BlackBerry/i.test(
      navigator.userAgent
    );
    if (isMobile) {
      // 当前网页在手机端打开
      dots = {
        nb: 50,
        distance: 70,
        d_radius: 100,
        array: []
      };
    }

    function colorValue(min) {
      return Math.floor(Math.random() * 255 + min);
    }

    function createColorStyle(r, g, b) {
      return "rgba(" + r + "," + g + "," + b + ", 0.8)";
    }

    function mixComponents(comp1, weight1, comp2, weight2) {
      return (comp1 * weight1 + comp2 * weight2) / (weight1 + weight2);
    }

    function averageColorStyles(dot1, dot2) {
      let color1 = dot1.color,
        color2 = dot2.color;

      let r = mixComponents(color1.r, dot1.radius, color2.r, dot2.radius),
        g = mixComponents(color1.g, dot1.radius, color2.g, dot2.radius),
        b = mixComponents(color1.b, dot1.radius, color2.b, dot2.radius);
      return createColorStyle(Math.floor(r), Math.floor(g), Math.floor(b));
    }

    function Color(min) {
      min = min || 0;
      this.r = colorValue(min);
      this.g = colorValue(min);
      this.b = colorValue(min);
      this.style = createColorStyle(this.r, this.g, this.b);
    }

    function Dot() {
      this.x = Math.random() * canvas.width;
      this.y = Math.random() * canvas.height;

      this.vx = -0.5 + Math.random();
      this.vy = -0.5 + Math.random();

      this.radius = Math.random() * 2;

      this.color = new Color(1);
    }

    Dot.prototype = {
      draw: function() {
        ctx.beginPath();
        ctx.fillStyle = this.color.style;
        ctx.arc(this.x, this.y, this.radius, 0, Math.PI * 2, false);
        ctx.fill();
      }
    };

    function createDots() {
      for (let i = 0; i < dots.nb; i++) {
        dots.array.push(new Dot());
      }
    }

    function moveDots() {
      for (let i = 0; i < dots.nb; i++) {
        let dot = dots.array[i];

        if (dot.y < 0 || dot.y > canvas.height) {
          dot.vx = dot.vx;
          dot.vy = -dot.vy;
        } else if (dot.x < 0 || dot.x > canvas.width) {
          dot.vx = -dot.vx;
          dot.vy = dot.vy;
        }
        dot.x += dot.vx;
        dot.y += dot.vy;
      }
    }

    function connectDots() {
      for (let i = 0; i < dots.nb; i++) {
        for (let j = 0; j < dots.nb; j++) {
          let i_dot = dots.array[i];
          let j_dot = dots.array[j];
          // 两个点之间的距离不能小于100
          if (
            i_dot.x - j_dot.x < dots.distance &&
            i_dot.y - j_dot.y < dots.distance &&
            i_dot.x - j_dot.x > -dots.distance &&
            i_dot.y - j_dot.y > -dots.distance
          ) {
            if (
              i_dot.x - mousePosition.x < dots.d_radius &&
              i_dot.y - mousePosition.y < dots.d_radius &&
              i_dot.x - mousePosition.x > -dots.d_radius &&
              i_dot.y - mousePosition.y > -dots.d_radius
            ) {
              ctx.beginPath();
              ctx.strokeStyle = averageColorStyles(i_dot, j_dot);
              ctx.moveTo(i_dot.x, i_dot.y);
              ctx.lineTo(j_dot.x, j_dot.y);
              ctx.stroke();
              ctx.closePath();
            }
          }
        }
      }
    }

    function drawDots() {
      for (var i = 0; i < dots.nb; i++) {
        var dot = dots.array[i];
        dot.draw();
      }
    }

    function animateDots() {
      ctx.clearRect(0, 0, canvas.width, canvas.height);
      moveDots();
      connectDots();
      drawDots();

      requestAnimationFrame(animateDots);
    }

    if(this.pagename) {
      // ----------------------跟着鼠标动--------------------
      document.getElementById(this.pagename).addEventListener("mousemove", function(e) {
        mousePosition.x = e.pageX;
        mousePosition.y = e.pageY;
      });
      document
        .getElementById(this.pagename)
        .addEventListener("mouseleave", function(e) {
          mousePosition.x = canvas.width / 2;
          mousePosition.y = canvas.height / 2;
        });
      // ----------------------跟着鼠标动--------------------
      createDots();
      requestAnimationFrame(animateDots);
    }
  }
}
</script>

<style lang="scss" scoped>
.bg-login {
    position: fixed;
    z-index: 1;
    height: 100%;
    width: 100%;
  .canvas {
    height: 100%;
    width: 100%;
  }
}

</style>